Automatic analyzers automatically make quantitative and qualitative analysis of biological samples such as blood and urine. Such automatic analyzers are in widespread use particularly in large hospitals and clinical laboratory centers which are required to process a large number of patient samples to be analyzed within a short time. The automatic analyzers have therefore been developed in large varieties covering from large, medium, to small sizes according to their processing capacities. In particular, some large-sized analyzer systems analyze large numbers of samples to be analyzed. Such a large-sized analyzer system incorporates a transfer line (transfer unit), via which a plurality of sample vessels, each of the sample vessels containing a sample to be analyzed, held in a holder called a sample rack is transported to a plurality of analyzers, to thereby automatically perform processes of up to an output of an analysis result when a laboratory technician has only to load the rack at a sample rack loading port.
In this case, the sample rack loaded at the sample rack loading port is transported by a belt conveyor-like transport line and a bar code reader disposed on the line recognizing a rack type and a sample for analysis during transport of the rack. An example of such an automatic analyzer system is disclosed in Patent Document 1.
Patent document 1 discloses a system including one transfer means for loading a rack into the analysis unit and the other transfer means for unloading the rack from the analysis unit, the system including an identification means arranged at the upstream side of the analysis unit. The identification means identifies a requested test item for a sample to thereby determine which analysis unit should be assigned for analysis and to instruct the analyzer module in question to receive the rack therein.
In patent document 2, each analysis unit includes a buffer on which racks or the like waiting are stored.